One problem associated with any data processing system is rigorous testing to ensure that the system operates within its design parameters. The most common form of testing is to use testcase programs which test particular aspects of the system. To write a testcase program by hand will require two to four weeks and as the number of testcase programs to test a system will be in the order of a thousand it can be seen that to manually produce testcase programs suitable for checking a large scale system requires a very large amount of effort.
United Kingdom Pat. Specification Nos. 1,479,122 and 1,510,240 describe methods of operating a computer to produce testcase programs.
U.K. Pat. Specification No. 1,479,122 describes a method of producing testcase programs in which statements are generated on a weighted random basis and a prediction is made to the value of variables changed during the operation of each statement. The programs produced by the method are suitable for testing the data calculating and manipulating aspects of a compiler Program. U.K. Pat. Specification No. 1,510,240 describes a method of producing testcase programs suitable for testing the input-output instruction handling capabilities of a compiler.
When a compiler is tested, the results of the run of a testcase appear either as a series of error messages at an I/O terminal or in a printout from a printer. An analysis of such messages gives an indication of any faults in the system.